The past loomed large in Hay-on-Wye on Wednesday; the day started with an entertaining scamper through the crusades with historian Tom Asbridge, after which our own Charlotte Higgins quizzed ancient historian Paul Cartledge about the contribution the Greeks made to democracy. Charlotte was back on stage later in the day, interviewing another ancient historian, Richard Miles, about the rise and fall of Carthage. She rounded them both up for a podcast chat as well – listen out for that on our Haycast later this week.

Later on, social historian David Kynaston jumped his audience forward a few millennia to the 1950s. Talking about the "golden ageism" of the period, he was clearly speaking to the converted – an audience who grew up during the 1950s, and groaned with joy at mentions of Dixon of Dock Green, and shouted out Grace Archer's name when Kynaston lost the thread of the story he was narrating.

Moving into the present, environmental writer Fred Pearce described current fears about overpopulation as "dangerous nonsense", while former Met commissioner Ian Blair – once a Sir, now a Lord – attempted to defend his controversial record as commissioner of the Metropolitan police. He said he "regrets" the shooting of innocent Brazilian Jean Charles de Menezes, an incident that "remains with" him. On the issue of the policing of protests, Blair said that in future, officers might have to use water cannons and tear gas to keep crowds disciplined – an idea he found "reprehensible" but possibly necessary. And when faced with a question about the licensing of guns, in the wake of the shootings in Cumbria yesterday, he said: "We have to accept we have the most draconian anti-gun laws in the world ... I don't think we can make it any tighter." Blair will be writing on this issue on Comment is free later on today.

Meanwhile, Nicholas Nassim Taleb joined our video team to discuss, among other things, why a cab driver knows as much as a political scientist about what's going to happen tomorrow.

On the literary side, Sarah Crown mused on the meaning of poetry, inspired by Simon Armitage and a lecture by Housman biographer Richard Perceval Graves; Oxford academic Daisy Hay told the audience about her explosive discovery of Claire Clairmont's 19th-century memoir, which describes Shelley and Byron as monsters; and Louis de Bernières explained why he wants to shoot Tony Blair.

Later today we'll be checking out the Puffin of Puffins debate, where bestselling authors will be championing their favourite Puffin of all time. Watch here for more details. And if you're so inclined, please let us know what you'd like to ask Nick Clegg when he appears at the festival this weekend.

We step into a parallel world, with Hay festival children's authors Mal Peet, Kjartan Poskitt and William Nicholson, while Julia Eccleshare assesses the longlist for the Guardian children's ficton prize